Project Summary/Abstract Abstract: This project will fund a five-day immersive workshop that will prepare junior and senior researchers alike to utilize the ABCD data for investigations of brain development in relation to mental health. The workshop will focus on training researchers on reproducible neuroimaging methods, predictive modeling approaches, and clinical mental health outcomes, with equal emphasis on theory and application. The workshop will be composed of instructional, tutorial, roundtable, break-out session, and open hacking components. Workshop attendees will immediately apply what they learn during the workshop by competing in a hackathon challenge to develop classification tools for mental health related outcomes based on brain imaging data, with attention to relevant social and environmental factors. The main outcome of this workshop will be that researchers leave with answers to questions about analyzing ABCD data with newly developed tools, with a deeper understanding of the theory behind these tools as well as analytic considerations for highly dimensional data. This will include training on methodological considerations regarding clinical outcomes and fostering collaboration between computational and clinical researchers across career stages. Another principal aim of this workshop is to contribute to national efforts to diversify the pool of highly trained biomedical researchers by recruiting a diverse group of attendees by eliminating participation barriers associated with social inequality, including financial burden, parenting, or disability, and by creating a safe and welcoming environment during the workshop. The immediate goal of this workshop is for attendees to acquire the following competencies: a) knowledge of analytical and statistical considerations specific to large, open datasets; b) how to conduct reproducible research, with emphasis on neuroimaging; c) knowledge of theory behind predictive modeling and ability to apply newly developed tools; d) design and execute investigations with clinically meaningful outcomes; e) identify social and environmental factors that impact the development of psychopathology; and f) communicate with researchers from diverse backgrounds and build interdisciplinary teams. The dissemination goals of the proposed workshop include publishing papers, presenting at conferences, and making any code or analytic techniques developed during the workshop available in online repositories for the broader research community. A long- term goal of this workshop is to form sustainable interdisciplinary networks between researchers from development, clinical, and computational backgrounds as these areas of expertise are all needed to advance our understanding of mental health.